1. Field of the Invention
This invention relates to a process for preparing 2'-methyl-2-haloacetanilides from ortho-(halomethyl) anilines and their anilinium salts by reaction with haloacetyl halides and subsequent catalytic reaction with hydrogen.
2. Description of the Prior Art
2-Haloacetanilide herbicides are known in the prior art and have been produced by haloacetylation of the appropriate amine generally in the presence of caustic soda to neutralize by-product hydrogen halide.
For example, in Hamm, et al., U.S. Pat. No. 2,863,752, a specific class of tertiary-2-haloacetanilide herbicides is prepared by gradually adding an acid chloride of a 2-haloacetic acid, e.g., chloroacetyl chloride, to excess N-substituted aniline. The secondary aniline is preferably dissolved in a suitable solvent, e.g., ethylene dichloride, mixed with aqueous sodium hydroxide and refrigerated. The reaction is conducted under refrigerated conditions to prevent an excessive rate of reaction. After the reaction, the recovered organic phase is successively washed with dilute acid, dilute base and water. The product 2-haloacetanilide is then recovered from the organic solvent by vacuum evacuation.
A similar process is described in Vogel, et al., U.S. Pat. No. 3,937,730 wherein a secondary aniline is reacted with an anhydride or acid halide of chloroacetic acid in the presence of a base; e.g., triethylamine.
In U.K. Patent Application No. GB 2,070,584 A, a secondary aniline is slowly added to a solution of an acid chloride (e.g. chloroacetyl chloride and methoxyacetyl chloride) in an inert solvent. The aniline is added at 20.degree.-80.degree. C. over the course of 0.5 to 1.5 hours. After subsequent evacuation in the same temperature range, to a pressure of 300-400 mm Hg, base neutralization, recovery of the organic phase and evaporative removal of the solvent, the product tertiary acetamide is recovered in the form of a melt.
None of these references describe a procedure for producing secondary 2-haloacetanilides from an ortho-(halomethyl) aniline or its anilinium salt.
Secondary haloacetanilides are useful as precursors for the production of N-(hydrocarbyloxymethyl)-2-haloacetanilide herbicides, particularly N-(ethoxymethyl)-2'-methyl-6'-(trifluoromethyl)-2-chloroacetanilide.
It is an object of the present invention to provide a new process for producing secondary 2-haloacetanilides.
It is another object of this invention to provide a process for producing secondary 2-haloacetanilides from an ortho-(halomethyl) aniline or its anilinium salt.
It is a further object of this invention to provide a method for producing secondary 2-haloacetanilides, preferably 2'-methyl-2-chloroacetanilides, which are useful for the preparation of specific aniline-derived herbicide compounds.
Other objects and advantages will become apparent from the following disclosure.